Ridged tubeless heat exchanger for fluid heating systems including a ridged component and methods of manufacture thereof

ABSTRACT

A heat exchanger including: a heat exchanger core including a top head, a bottom head, an first casing disposed between the top head and the bottom head, a second casing disposed between the top head and the bottom head and opposite an inner surface of the first casing, an inlet on the first casing, the second casing, or a combination thereof, and an outlet on the first casing, the second casing, or combination thereof, wherein at least one of the first casing and the second casing includes a ridge, and wherein the first casing and the second casing and define a flow passage between the inlet and the outlet; and a pressure vessel; an inlet member on the inlet, which connects the inlet to an outside of the pressure vessel; and an outlet member on the outlet, which connects the outlet to an outside of the pressure vessel.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. provisional patent application Ser. No. 62/124,235, filed on Dec. 11, 2014, the content of which is included herein by reference in its entirety.

BACKGROUND

1. Field of the Disclosure

This application relates to a ridged tubeless heat exchanger for a fluid heating system, methods of manufacture of the ridged tubeless heat exchanger, and fluid heating systems including the ridged tubeless heat exchanger.

2. Description of the Related Art

Heat exchangers are used in fluid heating systems to transfer heat from a thermal transfer fluid, such as a combustion gas produced by combustion of a fuel such as petroleum or natural gas, to a production fluid. The production fluid can then be used for a variety of commercial, industrial, or domestic applications such as hydronic, steam, and thermal fluid boilers, for example. Because of the desire for improved energy efficiency, compactness, and cost reduction, there remains a need for improved heat exchangers, and fluid heating systems including the same, as well as improved methods of manufacture thereof.

SUMMARY

Disclosed is a heat exchanger including: a heat exchanger core including a top head, a bottom head, a first casing disposed between the top head and the bottom head, a second casing disposed between the top head and the bottom head and opposite an inner surface of the first casing, an inlet on the first casing, the second casing, or a combination thereof, and an outlet on the first casing, the second casing, or combination thereof, wherein at least one of the first casing and the second casing includes a ridge, and wherein the first casing and the second casing define a flow passage between the inlet and the outlet; and a pressure vessel; an inlet member on the inlet, which connects the inlet to an outside of the pressure vessel; and an outlet member on the outlet, which connects the outlet to an outside of the pressure vessel, wherein the bottom head, the first casing and the second casing are contained entirely within the pressure vessel.

Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing including a slot; aligning the ridge and the slot by disposing the first casing on the second casing; rigidly attaching the ridge to the second casing; disposing a top head on a first end of the first casing and the second casing; disposing a bottom head on a second end of the first casing and the second casing; disposing an inlet on the first casing, the second casing, or a combination thereof; and disposing an outlet on the first casing, the second casing, or a combination thereof to manufacture the heat exchanger core, wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.

Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing member; disposing the second casing member on the first casing; rigidly attaching longitudinal edges of the second casing member to form a second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core; wherein the first casing and the second casing define a flow passage between the inlet and the outlet.

Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing member; disposing the second casing member on the first casing; rigidly attaching longitudinal edges of the second casing member to form a second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core; wherein the first casing and the second casing define a flow passage between the inlet and the outlet.

Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a first casing and a second casing; deforming at least one of the first casing and the second casing to form a ridge on at least one of the second casing and the first casing; heating or cooling the first casing or the second casing to expand or contract at least one of the first casing and the second casing; disposing the first casing on the second casing; thermally equilibrating the first casing and the second casing to contact the first casing and the second casing; disposing a top head on an upper end of each of the second casing and the first casing; disposing a bottom head on a lower end of each of the second casing and the first casing; disposing an inlet on the second casing, the first casing, or combination thereof; disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core; wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.

Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing, wherein an inner surface of the second casing including a groove, which is configured to receive the ridge; rotating the first casing relative to the second casing to thread the first casing into the second casing to dispose the first casing on the second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core, wherein the first casing and the second casing define a flow passage between the inlet and the outlet.

Also disclosed is a method of manufacturing a heat exchanger core, the method including: providing a first casing and a second casing; deforming at least one of the first casing and the second casing to form a ridge on at least one of an inner surface of the first casing and an inner surface of the second casing; disposing the first casing on the second casing; contacting the ridge and at least one of the inner surface of the first casing and the inner surface of the second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core, wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.

Also disclosed is a method of manufacturing a heat exchanger, the method including: providing the heat exchanger core; and disposing the heat exchanger core within a pressure vessel to manufacture the heat exchanger. A method of transferring heat between a first fluid and a second fluid, the method including: providing a heat exchanger according to claim 1; directing a first fluid into the inlet of the inner casing; and directing a second fluid into the pressure vessel inlet to exchange heat between the first fluid and the second fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages and features of this disclosure will become more apparent by describing in further detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1A is a schematic cut-away view of an embodiment of a heat exchanger;

FIG. 1B is a schematic cut-away view of another embodiment of the heat exchanger;

FIG. 2 is a cross-sectional diagram showing a top view of an embodiment of a first casing, a second casing, and a pressure vessel;

FIG. 3 is a schematic cut-away view of another embodiment of the heat exchanger;

FIG. 4 is a cross-sectional view of an embodiment of the heat exchanger;

FIG. 5 is a schematic cut-away view of another embodiment of the heat exchanger;

FIG. 6 is a schematic cut-away view of another embodiment of the heat exchanger;

FIG. 7 is a schematic cut-away view of another embodiment of the heat exchanger;

FIG. 8 is a cross-sectional view of an embodiment of a heat exchanger core comprising a ridge;

FIG. 9 is a cross-sectional view of another embodiment of the heat exchanger core comprising a ridge;

FIG. 10 is a perspective view of an embodiment of a slotted casing after rolling a flat sheet and prior to welding to form a cylinder;

FIG. 11 is a cross-sectional view of another embodiment of the heat exchanger core comprising a ridge;

FIG. 12 is a cross-sectional view of another embodiment of the heat exchanger core comprising a ridge;

FIG. 13 is a cross-sectional view of another embodiment of the heat exchanger core comprising a ridge; and

FIG. 14 is a cross-sectional view of an embodiment of the heat exchanger core.

DETAILED DESCRIPTION

Heat exchangers are desirably thermally compact, provide a high ratio of the thermal output to the total size of the heat exchanger, and have a design which can be manufactured at a reasonable cost. This is particularly true of gas-liquid heat exchangers, which can be incorporated into hydronic (e.g., liquid water), steam, and thermal fluid heating systems designed to deliver a hot fluid such as steam for temperature regulation, domestic hot water, or commercial or industrial process applications.

Tube-and-shell heat exchanger designs suffer a variety of drawbacks. In a tube-and-shell heat exchanger, the heat is transferred from the thermal transfer fluid, e.g., a combustion gas generated by a fuel-fired combustor and driven under pressure through the heat exchanger by a blower, to a production fluid (e.g., liquid water, steam, or another thermal fluid) across the walls of numerous thin-walled fluid conduits, i.e., tubes, having a wall thickness of less than 0.5 centimeters (cm). The tubes are rigidly connected to a tubesheet. Operational factors including thermal stress and corrosion lead to undesirable material failures in the tubes of tube-and-shell heat exchangers, the attachment points of the tubes, and in the tubesheets. Furthermore, when a failure occurs, the fluid heating system is rendered inoperable, and the thin-walled heat exchanger tubes and/or tubesheets are difficult and costly to service or replace, particularly in field installations.

Tubeless heat exchangers are also used. Tubeless heat exchangers avoid the use of the thin-walled tubes and the tubesheets associated with tube-and shell heat exchangers. Known practical designs for tubeless heat exchangers also have drawbacks. In available tubeless heat exchangers, the pressure vessel outer shell contacts a hot heat transfer fluid, e.g., along the exit path of the flue gas exhaust, resulting in a hot surface on the outside of the pressure vessel. To accommodate the hot outer surface, a refractory barrier outside the pressure vessel is provided, wherein the refractory barrier is separated from the pressure vessel by a gap through which the hot thermal transfer fluid flows, e.g., through an array of longitudinal ribs, thereby transferring thermal energy from the thermal transfer fluid into the outside of the shell, and ultimately transferring heat to the production fluid. Such tubeless designs suffer from refractory deterioration and loss of thermal efficiency due to some amount of heat being transferred into and through cracks in the refractory layer, and ultimately into the environment around the boiler. Additionally, flue gas, which can comprise CO, can leak through the cracks in the refractory layer and into occupied areas, instead of flowing to a flue gas discharge stack, creating health hazard. Furthermore, the hot outer surface of the pressure vessel presents safety issues due to the temperature of the skin which overlays the refractory material and due to leaking of thermal transfer fluid (e.g. flue gas) through cracks in the refractory material.

The disclosed heat exchanger provides a variety of features. For example, in the disclosed heat exchanger there is no direct contact between the thermal transfer fluid and the outer surface of the pressure vessel shell, thereby obviating the need for a refractory lining and avoiding safety, maintenance, and reliability concerns from a hot pressure vessel outer shell. Furthermore, the disclosed heat exchanger avoids use of thin-walled tubing, thereby avoiding the inherent fragility and susceptibility to material failure and corrosion of thin-walled tubing. The disclosed heat exchanger can be provided using metal alloy tubing having an average wall thickness of 0.5 to 5 cm, for example, as the primary member between the thermal transfer fluid and the production fluid, and thus can avoid the fragility problems associated with thin-walled tubing. In an embodiment, the disclosed heat exchanger can also avoid tight turnabouts in flow passages for both the thermal transfer fluid and the production fluid, thereby avoiding configurations that would be susceptible to fouling, clogging, and corrosion blockage. In addition, the disclosed heat exchanger provides for improved compactness (i.e., energy density, having the units of kilowatts per cubic meter, kW/m³) and improved performance characteristics compared to tube-and-shell heat exchanger alternatives of the same production capability. As is further disclosed herein, in an embodiment of the disclosed heat exchanger all outer surfaces of the heat exchanger core are contacted by the production fluid, thereby fully utilizing the outer surfaces of the heat exchanger core for thermal energy transfer and avoiding thermal stress in the heat exchanger core. The efficiency of the disclosed design provides for reduced material requirements and reduced manufacturing complexity.

A heat exchanger comprises: a heat exchanger core comprising a top head, a bottom head, an first casing disposed between the top head and the bottom head, a second casing disposed between the top head and the bottom head and opposite an inner surface of the first casing, an inlet on the first casing, the second casing, or a combination thereof, and an outlet on the first casing, the second casing, or combination thereof, wherein at least one of the first casing and the second casing comprises a ridge, and wherein the first casing and the second casing define a flow passage between the inlet and the outlet; and a pressure vessel; an inlet member on the inlet, which connects the inlet to an outside of the pressure vessel; and an outlet member on the outlet, which connects the outlet to an outside of the pressure vessel, wherein the bottom head, the first casing and the second casing are contained entirely within the pressure vessel, and wherein “inner surface” when used to indicate a surface of the first casing or the second casing is defined relative to the flow passage. Thus the inner surface of the first casing and the inner surface of the second casing, at least one of which comprises a ridge, define the flow passage. In an embodiment, the ridge connects the first casing and the second casing.

In an embodiment the first casing can be surrounded by the second casing, in which case the first casing may be an inner casing and the second casing may be an outer casing. Alternatively, the second casing can be surrounded by the first casing, in which case the second casing may be an inner casing and the first casing may be an outer casing. As shown in FIG. 1A, a heat exchanger 100 comprises: a heat exchanger core 110 comprising a top head 112; a bottom head 114; a first casing 116 disposed between the top head and the bottom head; a second casing 118 disposed between the top head and the bottom head, wherein an inner surface 116A of the first casing 116 is opposite an inner surface 118A of the second casing; an inlet 120 on the second casing; an outlet 122 on the first casing; wherein the first casing 116 comprises a ridge 124, wherein the first casing and the second casing define a flow passage between the inlet and the outlet; a pressure vessel 150; an inlet member 152 on the inlet and which connects the inlet to an outside of the pressure vessel; and an outlet member 154 on the outlet and which connects the outlet to an outside of the pressure vessel, wherein the bottom head, the first casing, and the second casing are contained entirely within the pressure vessel. The inner surface 116A of the first casing and the inner surface 118A of the second casing are opposite each other and are interior to the flow passage defined by the first casing 116 and the second casing 118. Also shown in FIG. 1A is the pressure vessel top head 160, the pressure vessel bottom head 162, and the pressure vessel shell 164, which is disposed between the pressure vessel top head and the pressure vessel bottom head. The pressure vessel top head, the pressure vessel bottom head, or combination thereof may comprise an opening for a conduit (not shown in FIG. 1A). The conduit is connected to the inlet member 152, and may pass through the pressure vessel top head 160 and the top head 112 of the heat exchanger core.

Another embodiment of the heat exchanger is shown in FIG. 1B. As shown in FIG. 1B, a curved inlet member 152A may be connected to an inlet 120A. Also shown in FIG. 1B is a conduit 170, which connects the inlet member to an outside of the heat exchanger. For example, as shown in FIG. 1B, the conduit may pass through the pressure vessel top head and the top head of the heat exchanger core.

In an embodiment the first casing comprises the ridge, which is disposed on an inner surface of the first casing and extends in a direction towards the second casing. Alternatively the second casing may comprise the ridge on an inner surface of the second casing and the ridge may extend towards the first casing. In yet another embodiment, both the first casing and the second casing comprise a ridge. In an embodiment wherein the first casing comprising the ridge, the ridge may contact the second casing. Alternatively, in an embodiment wherein the second casing comprises the ridge, the ridge may contact the first casing. In an embodiment, the contact forms an interference fit between the ridge and the surface it contacts. As is further disclosed below, the casing and the ridge are a single, unitary, indivisible part, as may be formed, for example, by deformation of the first casing or the second casing.

The first casing and the second casing may be coaxial, and may be concentric. In an embodiment, the first casing and the second casing are coaxial, as shown in FIG. 2. Non-coaxial configurations are also contemplated.

The first casing and the second casing of the heat exchanger core may have any suitable shape and may each independently have a circular cross-sectional shape, an elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semicircular cross-sectional shape, a square cross-sectional shape, a rectangular cross-sectional shape, a triangular cross-sectional shape, or combination thereof. For example, shown in FIG. 3 is an embodiment of a heat exchanger 300 comprising a heat exchanger core 310 having a triangular cross-sectional shape. An embodiment in which the first, e.g., inner, casing and the second, e.g., outer, casing each have a cylindrical shape is specifically mentioned.

In an embodiment, the first casing and the second casing may have a same cross-sectional shape, however other configurations are contemplated. For example, the heat exchanger core may comprise a first casing having a triangular cross-sectional shape and a second casing having a cylindrical cross-sectional shape.

The first casing and the second casing may each independently have any suitable dimensions. The first casing and the second casing may each independently have a largest outer diameter of 15 centimeters (cm), 25 cm, or 30 cm to 350 cm, 650 cm, or 1,400 cm, wherein the foregoing upper and lower bounds can be independently combined. For example, the first casing and the second casing may each independently have a largest outer diameter of 15 cm to 1,400 cm. An embodiment in which the first casing and the second casing each independently have a largest outer diameter of 30 cm to 350 cm is preferred. Alternatively, the first casing and the second casing may each independently have a largest outer diameter of 50 cm, 100 cm, or 200 cm to 500 cm, 700 cm, or 1,400 cm, wherein the foregoing upper and lower bounds can be independently combined.

The first casing and the second casing may each independently have a maximum height of 15 cm, 25 cm, or 30 cm to 350 cm, 650 cm, or 1,400 cm, wherein the foregoing upper and lower bounds can be independently combined, and wherein the height is determined in a direction of a major axis. For example, the first casing and the second casing may each independently have a maximum height of 15 cm to 1,400 cm. Alternatively, the first casing and the second casing may each independently have a height of 50 cm, 100 cm, or 200 cm to 500 cm, 700 cm, or 1,400 cm, wherein the foregoing upper and lower bounds can be independently combined.

An embodiment in which the first casing and the second casing each independently have a largest outer diameter of 30 cm to 350 cm and a height of 50 cm to 1,000 cm is preferred.

A top head is disposed on a first end of the first casing and the second casing, and a bottom head is disposed on a second opposite end of the first casing and the second casing. The top head and the bottom head may each independently be rigidly attached to the first casing and the second casing by any suitable method, such as by a weld, an adhesive, a fastener, or a combination thereof. An embodiment in which the top head and the bottom head are each welded to the first casing and the second casing is specifically mentioned. As shown in FIG. 1A, the top head and the bottom head of the heat exchanger are distinct members. However, other designs are contemplated. For example, the top head and the bottom head may each independently be formed by providing a weld seam between the first casing and the second casing. Alternatively, the ends of the first casing and the second casing may be contacted, e.g., pinched together or rolled, to form the top head and the bottom head.

A thickness, e.g., an average thickness, of the top head, the bottom head, the first casing, and the second casing may be any suitable dimension, and the thickness of the top head, the bottom head, the first casing, and the second casing may each independently be 0.5 cm to 3 cm, or 0.5 cm, 0.6 cm, 0.7 cm, or 1 cm to 5 cm, 4 cm, 3.5 cm, or 3 cm, wherein the foregoing upper and lower bounds can be independently combined. An embodiment in which the top head, the bottom head, the first casing, and the second casing each independently have a thickness of 0.5 cm to 1 cm is specifically mentioned.

An inner surface 116A of the first casing 116, an inner surface 118A of the second casing 118, at least one of which comprises the ridge 124, define a flow passage between the inlet and the outlet of the heat exchanger core, which comprises, e.g., consists of, the first casing, the second casing, the rib, and the top head and the bottom head of the heat exchanger core. It has been surprisingly discovered that certain configurations of the flow passage provide improved performance, including a desirable combination of pressure drop between the inlet and the outlet, and thermal performance. This improvement can be parameterized in terms of an aspect ratio of the flow passage, wherein the aspect ratio of the flow passage defined as the maximum centerline dimension divided by the minimum centerline dimension of the flow passage, where both dimensions are determined normal to a flow direction and perpendicular to each other, and wherein the shorter dimension is defined at the midpoint of the longer dimension. It has been further surprisingly discovered that configurations wherein an aspect ratio of the flow passage is 3 to 500, e.g., 3, 5, 10, 15, or 20 to 500, 200, 100, 90, or 80, preferably 10 to 100, more preferably 20 to 80, provide an improved combination of pressure drop and thermal performance, wherein the foregoing upper and lower bounds can be independently combined. Determination of the aspect ratio is illustrated in FIG. 4, which indicates determination of the height H and the width W of an embodiment of the flow passage. As shown in FIG. 4, the height H can be determined between opposite surfaces of a same ridge, e.g., between a first ridge surface 124A, and a second ridge surface 124B when viewed in a cross-sectional dimension, and the width W is determined between and inner surface 116A of the first casing 116 and an inner surface 118A of the second casing 118. Alternatively, for example when a plurality of ridges are used, the height H can be determined between opposite surfaces of neighboring ridges. For example, the height H of the flow passage may be 0.6 cm to 600 cm, and may be 0.6 cm, 1 cm, 2 cm, 4 cm, 10 cm, 20 cm, 40 cm, 80 cm, or 160 cm to 600 cm, 550 cm, 500 cm, 450 cm, 400 cm, 350 cm, 300 cm, or 250 cm, wherein the foregoing upper and lower bounds can be independently combined. Also the width may be 0.6 cm to 600 cm, and may be 0.6 cm, 1 cm, 2 cm, 4 cm, 10 cm, 20 cm, 40 cm, 80 cm, or 160 cm to 600 cm, 550 cm, 500 cm, 450 cm, 400 cm, 350 cm, 300 cm, or 250 cm, wherein the foregoing upper and lower bounds can be independently combined. In a preferred embodiment, the height is 20 cm to 60 cm and the width is 1 cm to 4 cm. In a more preferred embodiment, the height is 40 cm to 45 cm and the width is 1.2 cm to 1.9 cm. In another more preferred embodiment, the height is 45 cm to 50 cm and the width is 1.5 cm to 3 cm

Any suitable number of ridges may be used. For example, as shown in FIG. 1A, a single ridge may be used. Alternatively as shown in FIG. 5, a plurality of ridges may be used, such as 2 to 100 ridges, e.g., 2, 4, or 8 to 100, 50, or 10 ridges, wherein the foregoing upper and lower bounds can be independently combined. Also, the ridge may have any suitable configuration. In an embodiment, the ridge may have a helical shape, a stepped shape, a shape of a segment of a circle, a shape of a segment of a helix, or a combination thereof. For example, as shown in FIG. 1, the ridge 124 may have a helical shape. As shown in FIG. 3, a ridge 324 may have a spiral triangular shape. Alternatively, as shown in FIG. 5, a ridge 524 may have a shape of a segment of a circle. Alternatively, as shown in FIG. 6, a ridge 624 may have a stepped shape. In yet another embodiment, as shown in FIG. 7, a ridge 724 may have a linear shape.

The ridge may have any suitable cross-sectional shape and, and may be curvilinear, rectilinear, or combination thereof. In an embodiment, the ridge 124 may have a semi-circular cross-sectional shape as shown in FIG. 8. Alternatively, the ridge may have a semi-elliptical cross-sectional shape, a semi-oval cross-sectional shape, a semi-stadium cross-sectional shape, a square cross-sectional shape, a rectangular cross-sectional shape, a triangular cross-sectional shape, or combination thereof.

The ridge may have any suitable cross-sectional dimensions. In an embodiment in which ridge is rectilinear, the ridge may have a cross-sectional height of 0.3 cm to 600 cm, e.g., 0.3 cm, 0.5 cm, 0.6 cm, 1 cm, 10 cm, or 50 cm to 100 cm, 200 cm, 400 cm, or 600 cm, wherein the foregoing upper and lower bounds can be independently combined and a width of 0.3 cm to 600 cm, e.g., 0.3 cm, 0.5 cm, 0.6 cm, 1 cm, 10 cm, or 50 cm to 200 cm, 400 cm, or 600 cm, wherein the foregoing upper and lower bounds can be independently combined. In a preferred embodiment, the ridge has a height of 0.5 cm to 3 cm and a width of 0.5 cm to 3 cm. The height can be measured in a direction perpendicular a longitudinal or major axis of the heat exchanger core and the width can be measured in a direction parallel to the longitudinal axis of the heat exchanger core. In a preferred embodiment which the ridge is semicircular, as shown in FIG. 8, the ridge may have a height p of 0.3 cm to 600 cm, e.g., 0.3 cm, 0.5 cm, 0.6 cm, 1 cm, 10 cm, or 50 cm to 200 cm, 400 cm, or 600 cm, wherein the foregoing upper and lower bounds can be independently combined and a width a of 0.3 cm to 600 cm, e.g., 0.3 cm, 0.5 cm, 0.6 cm, 1 cm, 10 cm, or 50 cm to 200 cm, 400 cm, or 600 cm, wherein the foregoing upper and lower bounds can be independently combined. In a preferred embodiment, the ridge has a height p of 0.5 cm to 3 cm and a width of 0.5 cm to 3 cm.

The ridge disposed on the first casing may contact the second casing, and a ridge disposed on the second casing may contact the first casing. In an embodiment, a ridge on the first casing may form an interference fit with the inner surface of the second casing. Alternatively, a ridge on the second casing may form an interference fit with an inner surface of the first casing. In an embodiment, the first casing and the second casing each comprise a ridge. In an embodiment in which the first casing comprises the ridge, the ridge may be rigidly attached to the second casing. Also, in an embodiment in which the second casing comprises the ridge, the ridge may be rigidly attached to the first casing. The attachment may be provided by any suitable attachment member, such as a weld, an adhesive, a fastener, or combination thereof. Use of a weld, such as a spot weld or a stitch weld is specifically mentioned. The ridge may be stitch-welded to the opposite of the first casing or the second casing anywhere along its length, or continuously welded along its length, to attach the ridge in a selected position to the opposite casing. The weld may transverse an entire length of the ridge, or may be present on a portion of the ridge, such as 10% to 100% of the total ridge length, e.g., 10%, 15%, or 20% to 100%, 90%, 80%, or 70% of the total ridge length, wherein the foregoing upper and lower bounds can be independently combined. An embodiment in which the weld transverses 100% of the total ridge length is specifically mentioned. Also, in an embodiment in which the first casing comprises a first ridge and in which the second casing comprises a second ridge, the first ridge may be rigidly attached to the second casing by a first weld, and the second ridge may be rigidly attached to the first casing by a second weld, wherein the first weld and the second weld may be the same type of weld or may be different types of welds.

If desired, the ridge may further comprise a connecting member, wherein the connecting member rigidly connects the ridge and the opposite casing. The connecting member may be a weld, adhesive, a fastener, or combination thereof. Use of a weld is specifically mentioned. For example, as shown in FIG. 9, the ridge may comprise a cut 910 configured to accept a weld that fills the gap and rigidly connects the ridge to the opposite casing. The cut may have any suitable shape, and may be beveled as shown in FIG. 9. In an embodiment, a seam weld may be used and connect the ridge to the opposite casing.

In an embodiment, a slotted casing may be used to facilitate attachment of the ridge. Shown in FIG. 10 is an embodiment of a slotted casing 1010 comprising a slot 1020 after rolling a flat sheet and prior to welding the opposite longitudinal edges to form a cylinder. Also shown in FIG. 10, is an outlet 1030, which may be optionally provided if desired. As shown in FIG. 11, use of a slotted casing facilitates access to the ridge. As shown in FIG. 11, a weld 1110 may be used to rigidly attach the ridge to an opposite casing. For example, as shown in FIG. 11 in an embodiment in which the ridge 1100 is disposed on a first casing 1120, the ridge may be welded to a slotted second casing 1130.

In another embodiment, the first casing, the second casing, or combination thereof may comprise a casing deformation which forms an interference fit with the ridge. For example, as shown in FIG. 12, a first casing 1210 may comprise a ridge 1220, and a second casing 1230 may comprise a deformation 1240 on an inner surface of the second casing, which forms an interference fit with the ridge 1220.

In yet another embodiment, the first casing, the second casing, or combination thereof may comprise a groove which is configured to accept the ridge. For example, as shown in FIG. 13, a first casing 1310 may comprise a ridge 1320, and a second casing 1330 may comprise a groove 1340 on an inner surface of the second casing, which is configured to accept the ridge 1320.

The rib may have a pitch, e.g., a slope, having any suitable angle with respect to a longitudinal axis of the heat exchanger core, the inner casing, or the outer casing. As illustrated in FIG. 1A, a pitch θ may be defined with respect to a tangent direction t, wherein the tangent direction is perpendicular to a longitudinal axis of the outer casing. In an embodiment, a pitch of the rib is 0 degrees to 90 degrees with respect to the tangent direction, and can be 0 degrees, 2 degrees, or 5 degrees to 90 degrees, 50 degrees, or 45 degrees with respect to the tangent direction, wherein the foregoing upper and lower bounds can be independently combined. A pitch of 5 degrees to 45 degrees with respect to the tangent direction is specifically mentioned. In an embodiment, the heat exchanger core comprises a plurality of ribs, and a pitch of each rib of the plurality of ribs may each independently be 0 degrees to 90 degrees with respect to the tangent direction, and can be 0 degrees, 2 degrees, or 5 degrees to 90 degrees, 50 degrees, or 45 degrees with respect to the tangent direction, wherein the foregoing upper and lower bounds can be independently combined. An embodiment in which the pitch is 5 degrees to 45 degrees with respect to the tangent direction is specifically mentioned. In yet another embodiment, as shown in FIG. 7, the ridge may be parallel to an axis, e.g., a longitudinal axis, of the first casing, the second casing, or combination thereof. In an embodiment, the heat exchanger core may comprise a plurality of ridges, and each ridge may be parallel to a longitudinal axis of the first casing, the second casing, or combination thereof, for example as illustrated by ridge 724 as shown in FIG. 7. In an embodiment, the heat exchanger core comprises a ridge which provides a serpentine flow passage between the inlet and the outlet. The serpentine flow passage may be defined by a plurality of linear ridges, or may be defined by a combination of curved ridges and linear ridges.

For certain applications, such as to satisfy inspection requirements, a third casing may be desirable. Shown in FIG. 13 is an embodiment comprising a first casing 1310, a second casing 1320, and a third casing 1330, wherein the third casing is disposed adjacent to an outer surface of the second casing 1320 and between the top head and the bottom head of the heat exchanger core. Alternatively, the third casing may be adjacent a concave outer surface of the first casing 1310, wherein the first casing is an inner casing, if desired. Any suitable configuration of the first casing, the ridge, and the second casing may be used in conjunction with the third casing. In yet another embodiment, shown in FIG. 14, the first casing 1410, the second casing 1420, and the third casing 1430 may be used in conjunction with a vertical ridge 1440.

The third casing may comprise a same material as is disclosed for the first casing, and may be manufactured using a same method as is disclosed for the first casing, and thus duplicative disclosure of the content and manufacture the third casing is not repeated for clarity.

The bottom head, the first casing, and the second casing of the heat exchanger core are contained entirely within the pressure vessel. In another embodiment, the top head, the bottom head, the first casing, and the second casing of the heat exchanger core are contained entirely within the pressure vessel. In yet another embodiment, an entirety of the heat exchanger core, i.e., the top head, the bottom head, the first casing, the second casing, the inlet, and the outlet are contained entirely within the pressure vessel. As used with respect to the configuration of the heat exchanger core within the pressure vessel, “entirety” means that the component referred to is fully contained within the pressure vessel. For example, when the pressure vessel is filled with a fluid, an entire outer surface of a component of the heat exchanger core which is contained entirely with the pressure vessel would be contacted by the fluid. Thus in use, e.g., when the pressure vessel is filled with a production fluid, an entirety of an outer surface 115 of the bottom head, an entirety of an outer surface 119 of the first casing, and an entirety of an outer surface 117 of the second casing can be contacted by the production fluid. In yet another embodiment the top head may also be contained entirely within the pressure vessel, in which case when the pressure vessel is filled with a production fluid, the production fluid contacts an entire outer surface 113 of the top head as well. In yet another embodiment, an entirety of the heat exchanger core, i.e., the top head, the bottom head, the first casing, the second casing, the inlet, and the outlet, are contained entirely within the pressure vessel.

The heat exchanger further comprises an inlet member 152 or 152A which connects the inlet 120 or 120A, respectively, to an outside of the pressure vessel, e.g. for providing a flow of a thermal transfer fluid, such as a combustion gas, to the inlet of the heat exchanger core. Also, an outlet member 154 which connects the outlet 122 of the heat exchanger core to an outside of the pressure vessel can be provided. Also, the pressure vessel comprises an inlet 155, and an outlet 156 for providing a flow of a production fluid into and out of the pressure vessel.

The top head, the bottom head, the first casing, the second casing, the inlet, the outlet, the pressure vessel, the inlet member, and the outlet member, can each independently comprise any suitable material. Use of a metal is specifically mentioned. Representative metals include iron, aluminum, magnesium, titanium, nickel, cobalt, zinc, silver, copper, and an alloy comprising at least one of the foregoing. Representative metals include carbon steel, mild steel, cast iron, wrought iron, a stainless steel such as a 300 series stainless steel or a 400 series stainless steel (e.g., 304, 316, or 439 stainless steel), Monel, Inconel, bronze, and brass. Specifically mentioned is an embodiment in which the heat exchanger core and the pressure vessel each comprise steel, specifically mild steel.

The heat exchanger may be used to exchange heat between any suitable fluids, i.e., a first fluid and the second fluid, wherein the first and second fluids may each independently be a gas or a liquid. Thus the disclosed heat exchanger may be used as a gas-liquid, liquid-liquid, or gas-gas heat exchanger. In a preferred embodiment the first fluid, which is directed through the heat exchanger core, is a thermal transfer fluid, and may be a combustion gas, e.g., a gas produced by fuel fired combustor, and may comprise water, carbon monoxide, carbon dioxide, or combination thereof. Also, the second fluid, which is directed through the pressure vessel and the contacts an entire outer surface of the heat exchanger core, is a production fluid and may comprise water, steam, oil, a thermal fluid, or combination thereof. The thermal fluid may comprise an ester, a diester, a glycol, a silicone, water, a petroleum oil, a mineral oil, or a chlorofluorocarbon such as a halogenated fluorocarbon, a halogenated chlorofluorocarbon, or a perfluorocarbon. A combination comprising at least one of the foregoing may be used. A thermal fluid comprising glycol and water is specifically mentioned. For example, the thermal fluid may be formulated from an alkaline organic or inorganic compound and used in diluted form with a concentration ranging from 3 weight percent to 10 weight percent, based on a total weight of the thermal fluid.

For example, the second fluid may comprise water, and may be used as a production fluid in a domestic, commercial, or industrial heating application. The first fluid, e.g., the thermal transfer fluid, which is directed through the inlet member, through the flow passage of the heat exchanger core, and out the outlet member, does not contact the pressure vessel. As a result, thermal heat energy transfer occurs between the hot first fluid flowing inside the core to the second fluid separately flowing in the pressure vessel. As noted above, the second fluid contacts an entire outer surface of the of the heat exchanger core and at no point does the surface of the pressure vessel contact the first fluid. Because the pressure vessel does not contact the first fluid, which can have a temperature of 10° C. to 1800° C., such as 10° C., 50° C., 100° C., 200° C., or 400° C. to 1800° C., 1600° C., 1400° C., 1200° C., or 1000° C., wherein the foregoing upper and lower bounds can be independently combined, the exterior surface of the pressure vessel remains relatively cool and use of insulation, e.g., a refractory material, to insulate the pressure vessel can be avoided. An embodiment in which the first fluid has a temperature of 100° C. to 1350° C. is specifically mentioned.

The pressure vessel top head, the pressure vessel bottom head, and the pressure vessel shell may each independently have any suitable shape, and may be rectilinear or curvilinear, and may be flat, domed, or spherical. For example, as shown in FIG. 1A, the pressure vessel top head and the pressure vessel bottom head may have a flat shape. Alternatively, as shown in FIG. 1B, the pressure vessel top head and the pressure vessel bottom head may have a curved shape. Also, the pressure vessel shell may have any suitable shape, may be curvilinear or rectilinear, and may be cylindrical as shown in FIG. 1A.

Also disclosed is a method of manufacturing a heat exchanger core, the method comprising: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing comprising a slot; aligning the ridge and the slot by disposing the first casing on the second casing; rigidly attaching the ridge to the second casing; disposing a top head on a first end of the first casing and the second casing; disposing a bottom head on a second end of the first casing and the second casing; disposing an inlet on the first casing, the second casing, or a combination thereof; and disposing an outlet on the first casing, the second casing, or a combination thereof to manufacture the heat exchanger core, wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet. In an embodiment the first casing is in inner casing. Alternatively, the first casing may be an outer casing. The flow passage may be defined by the inner surface of the first casing and the inner surface of the second casing, wherein at least one of the first casing and the second casing comprises the ridge.

The first casing may be a tube or a section of a pipe, for example, and may be provided by rolling a flat sheet and connecting opposite edges to provide a tube. The ridge may be disposed on the inner surface of the first casing by any suitable method, such as by stamping or hydraulic deformation, for example. As shown in FIG. 10, the second casing 1010 may comprise a slot 1020, and optionally an outlet 1030, and may be formed from a rolled flat sheet. The second casing may be provided, for example, by cutting a slot at a selected pitch angle in a pipe, or by cutting a slot in a flat sheet and then forming a tube by rolling the flat sheet into a cylinder and then connecting, e.g., welding, opposite longitudinal edges to form the cylinder. The slot may have a width selected to correspond to a dimension of the ridge. In an embodiment, a width of the slot is 1 millimeter (mm) to 5 centimeters (cm), e.g., 1 mm, 2 mm, or 4 mm to 5 cm, 3 cm, or 1 cm, wherein the foregoing upper and lower bounds can be independently combined. An embodiment in which a width of the slot is to 2 millimeters to 2 cm is specifically mentioned. Also, in an embodiment the slot may comprise a bevel to facilitate the formation of a butt weld between the casing and the ridge. The casing comprising the slot may be disposed on the casing comprising the ridge and then the ridge rigidly attached to the casing comprising the slot by welding, for example. Use of a full penetration weld or butt weld is specifically mentioned, and the weld may be selected based upon the shape and dimensions of the ridge. The top head of the heat exchanger core may be welded to the first end of each of the first casing and the second casing, and the bottom head of the heat exchanger core welded to the opposite second end of each of the first casing and the second casing, for example, to form a cavity between the first casing and the second casing for the thermal transfer fluid. The inlet and the outlet may each independently be disposed, e.g., welded, on the first casing the second casing or combination thereof. An embodiment in which the inlet is disposed on an outer surface of the first casing, and in which the outlet is disposed on an outer surface of the second casing is specifically mentioned. Also, if desired, an inlet member, which connects the inlet to an outside of the pressure vessel, e.g., to a source of a thermal transfer fluid, may be disposed on the inlet. In addition, an outlet member, which connects the outlet to an outside of the pressure vessel, e.g., to a vent, may be disposed on the outlet.

In an embodiment, the dimensions of the ridge and the dimensions of the gap in the slotted casing may be selected so that when the first and second casings are in their final positions, an outer surface of the ridge protrudes up to, or beyond, an outer surface of the second casing. The ridge and the second casing may be rigidly attached using a seam weld, for example.

In another embodiment, the method of manufacturing a heat exchanger core comprises providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing member; disposing, e.g., wrapping, the second casing member on the first casing, e.g., on an outer surface of the first casing; rigidly attaching longitudinal edges of the second casing member to form a second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the first casing, the second casing, or combination thereof; and disposing an outlet on the first casing, the second casing, or combination thereof to manufacture the heat exchanger core; wherein the first casing, which comprises a ridge, and the second casing define a flow passage between the inlet and the outlet. The flow passage may be defined by an inner surface of the first casing and an inner surface of the second casing, wherein the first casing comprises the ridge. In an embodiment, the first casing is an inner casing and the second casing is outer casing. Alternatively, the first casing may be an outer casing and the second casing may be in inner casing. The disposing of the second casing member on the first casing may comprise wrapping the second casing member on an inner surface, e.g., a convex surface the first casing. Alternatively, the disposing of the second casing member on the first casing may comprise bending the second casing member and disposing the second casing member on an inner surface, e.g., a concave surface, of the first casing. Details of the disposing are similar to as disclosed above, and thus repeated description is not included for clarity.

If desired, a third casing may be disposed on an outer surface of the second casing, as shown in FIG. 13. A method of disposing the third casing is the same as disclosed for the second casing, and repetitive disclosure is not included herein for clarity.

The casing comprising a slot may be provided from a flat metal sheet. In an embodiment, the providing the casing comprising the slot comprises providing a metal sheet, cutting a slot in the metal sheet, wherein a direction of the slot forms an angle of 0 degrees to 90 degrees, e.g., 0 degrees, 2 degrees, or 5 degrees to 90 degrees, 50 degrees, or 45 degrees with respect to a longitudinal edge of the metal sheet, wherein the foregoing upper and lower bounds can be independently combined, bending the metal sheet so that longitudinal edges of the metal sheet are adjacent each other, and joining the longitudinal edges to provide the outer casing comprising the slot and the outlet. An embodiment in which a direction of the slot forms an angle of about 2 degrees to 45 degrees with respect to the longitudinal edge of the metal sheet is specifically mentioned. The configuration and angle of the slot may be selected to correspond to a pitch angle of the ridge. The longitudinal edges may be defined using a seam weld, for example. If desired, the method may further comprise cutting an opening in the metal sheet to form the outlet. The dimensions of the metal sheet may be selected in accordance with a desired diameter of the outer casing.

Alternatively, the heat exchanger core can be manufactured by heating an outer casing of the first and second casings to thermally expand the outer casing, or cooling an inner casing of the first and second casings to contract the inner casing, disposing the first casing on the second casing, and then thermally equilibrating the first casing and the second casing. In an aspect, a method of manufacturing a heat exchanger core comprises providing a first casing and a second casing; deforming at least one of the first casing and the second casing to form a ridge on at least one of the second casing and the first casing; heating or cooling the first casing or the second casing to expand or contract at least one of the first casing and the second casing; disposing the first casing on the second casing; thermally equilibrating the first casing and the second casing to contact the first casing and the second casing; disposing a top head on an upper end of each of the second casing and the first casing; disposing a bottom head on a lower end of each of the second casing and the first casing; disposing an inlet on the second casing, the first casing, or combination thereof; disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core; wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.

The casing which is heated, e.g., the first casing or the second casing, may be heated to 200° C. to 2000° C., e.g., 200° C., 300° C., or 400° C. to 2,000° C., 1,000° C., 800° C., or 600° C., wherein the foregoing upper and lower bounds can be independently combined, to expand the casing so that it may be disposed around the colder other casing, e.g., the second casing or the first casing. Heating to 300° C. to 800° C. is specifically mentioned. Once the second casing is in its desired position, it may be allowed to cool and contract and form an interference fit between the ridge and an inner surface of the second casing. Alternatively or in addition, the first casing or the second casing may be cooled to −196° C. to 0° C., e.g., −196° C., −150° C., or −80° C. to −20° C., −10° C., 0° C., 10° C., 20° C., wherein the foregoing upper and lower bounds can be independently combined, to contract an inner casing of the first casing or the second casing so that may be disposed within the hotter other casing. Cooling to −150° C. to 20° C. is specifically mentioned. Thermally equilibrating the first casing and the second casing can form an interference fit between the ridge and an inner surface of the second casing.

In yet another aspect, the first casing, the second casing, or a combination thereof may be deformed to contact the ridge and the opposite casing. In an aspect, the method of manufacturing a heat exchanger core comprises providing a first casing; disposing a ridge on an inner surface of the first casing; disposing a second casing on the first casing; deforming at least one of the first casing and the second casing to contact the second casing and the ridge; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the first casing, the second casing, or combination thereof; and disposing an outlet on the first casing, the second casing, or combination thereof to manufacture the heat exchanger core, wherein the first casing and the second casing define a flow passage between the inlet and the outlet.

The deforming may comprise providing a concave surface or a convex surface. The casing comprising the deformation may be provided by disposing a casing member on the first casing, which comprises the ridge, and then compressing or expanding the casing member to form a second casing comprising a concave surface directed towards the first casing. Alternatively, the casing member may be deformed, for example by stamping, to provide a casing member comprising a convex surface. In yet another embodiment, the first casing may be expanded, e.g., hydraulically or pneumatically, for example, or contracted by crushing, for example, to expand or contract the first casing and the ridge so that the ridge contacts the second casing. The pressure, force or stress applied to achieve the required deformation depends upon a variety of factors including geometry, dimension, component materials and manufacturing method used to dispose the first and second casings. Specifically, the magnitude of the pressure, force, or stress can be determined based on the yield stress of the component materials undergoing deformation using industry standard methods and data known to persons of skill in the art of manufacturing.

In yet another embodiment, a method of manufacturing the heat exchanger core comprises providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing, wherein an inner surface of the second casing comprises a groove, which is configured to receive the ridge; rotating the first casing relative to the second casing to thread the first casing into the second casing to dispose the first casing on the second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core, wherein the the first casing, which comprises the ridge, and the second casing define a flow passage between the inlet and the outlet.

The groove may be a spiral groove and may be configured to permit screwing the first casing onto the second casing. The groove may be provided by any suitable method, such as machining, casting or deformation.

The first casing may be an inner casing, and the second casing may be an outer casing. Alternatively, the first casing may be an outer casing, and the second casing may be an inner casing.

Also disclosed is a method of manufacturing a heat exchanger core, the method comprising: providing a first casing and a second casing; deforming at least one of the first casing and the second casing to form a ridge on at least one of an inner surface of the first casing and an inner surface of the second casing; disposing the first casing on the second casing; contacting the ridge and at least one of the inner surface of the first casing and the inner surface of the second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core, wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.

The deforming may comprise deforming the first casing to form a ridge on the inner surface of the first casing, and the contacting may comprise contacting the ridge and an inner surface of the second casing by inserting the first casing into the second casing. Alternatively, the disposing may comprise disposing the first casing on the second casing; and then deforming the first casing to form a ridge on an inner surface of the first casing and to contact the ridge and an inner surface of the second casing. In yet another embodiment, the deforming may comprise expanding the first casing in a direction towards the second casing. The deforming may be provided by stamping, hydraulic deformation, pneumatic deformation, molding, or combination thereof.

In yet another embodiment, the deforming may comprise deforming the inner wall of the first casing to form a ridge directed towards an inner wall of the second casing, and the method may further comprise forming a cut in an apex of the ridge, and welding the ridge to the inner wall of the second casing.

As noted above, the first casing may be an inner casing and the second casing may be an outer casing, or alternatively the first casing may be an outer casing and the second casing may be an inner casing.

Also disclosed is a method of manufacturing a heat exchanger, the method comprising: providing the heat exchanger core; and disposing the heat exchanger core within a pressure vessel to manufacture the heat exchanger. The pressure vessel may comprise a pressure vessel top head, a pressure vessel bottom head, and a shell disposed between the pressure vessel top head and the pressure vessel bottom head, wherein the pressure vessel top head, the pressure vessel bottom head, and the shell, or a combination thereof comprises a pressure vessel inlet, and wherein the pressure vessel top head, the pressure vessel bottom head, and the shell comprises a pressure vessel outlet. In an embodiment, the pressure vessel inlet may be disposed in the pressure vessel bottom head, and the pressure vessel outlet may be disposed in the pressure vessel top head.

Also disclosed is a method of transferring heat between a first fluid and a second fluid, the method comprising: providing the heat exchanger; directing a first fluid into the inlet of the inner casing; and directing a second fluid into the pressure vessel inlet to exchange heat between the first fluid and the second fluid.

The invention has been described with reference to the accompanying drawings, in which various embodiments are shown. This invention may, however, be embodied in many different forms, and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout.

It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. Also, the element may be on an outer surface or on an inner surface of the other element, and thus “on” may be inclusive of “in” and “on.”

It will be understood that, although the terms “first,” “second,” “third,” etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer,” or “section” discussed below could be termed a second element, component, region, layer, or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes,” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims. 

What is claimed is:
 1. A heat exchanger comprising: a heat exchanger core comprising a top head, a bottom head, a first casing disposed between the top head and the bottom head, a second casing disposed between the top head and the bottom head and opposite an inner surface of the first casing, an inlet on the first casing, the second casing, or a combination thereof, and an outlet on the first casing, the second casing, or combination thereof, wherein at least one of the first casing and the second casing comprises a ridge, and wherein the first casing and the second casing and define a flow passage between the inlet and the outlet; and a pressure vessel; an inlet member on the inlet, which connects the inlet to an outside of the pressure vessel; and an outlet member on the outlet, which connects the outlet to an outside of the pressure vessel, wherein the bottom head, the first casing and the second casing are contained entirely within the pressure vessel.
 2. The heat exchanger of claim 1, wherein the inner surface of the first casing is opposite an inner surface of the second casing, and wherein the ridge connects the first casing and the second casing.
 3. The heat exchanger of claim 1, wherein the first casing comprises the ridge on the inner surface of the first casing, wherein the ridge extends towards the second casing, or wherein the second casing comprises the ridge on an inner surface of the second casing, wherein the ridge extends towards the first casing.
 4. The heat exchanger of claim 3, wherein the first casing comprises the ridge, wherein the ridge contacts the second casing, and wherein first casing and the ridge are a single, unitary indivisible component.
 5. The heat exchanger of claim 3, wherein the first casing comprises the ridge and the ridge contacts the second casing, or wherein the second casing comprises the ridge and the ridge contacts the first casing.
 6. The heat exchanger of claim 1, wherein the ridge forms an interference fit with the inner surface of the first casing or the inner surface of the second casing.
 7. The heat exchanger of claim 1, wherein the ridge further comprises a connecting member, wherein the connecting member rigidly connects the ridge to at least one of the second casing and the first casing.
 8. The heat exchanger of claim 7, wherein the connecting member is a weld.
 9. The heat exchanger of claim 1, wherein the ridge is a product of deforming at least one of the first casing and the second casing.
 10. The heat exchanger of claim 1, wherein the heat exchanger comprises a plurality of ridges.
 11. The heat exchanger of claim 1, wherein the ridge has a helical shape, a stepped shape, a shape of a segment of a circle, a shape of a segment of a helix, or a combination thereof.
 12. The heat exchanger of claim 11, wherein the ridge has a curvilinear cross-sectional shape, a rectilinear cross-sectional shape, or combination thereof.
 13. The heat exchanger of claim 1, wherein a pitch of the ridge is 0 degrees to 90 degrees with respect to a tangent direction, wherein the tangent direction is perpendicular to a longitudinal axis of the first casing.
 14. The heat exchanger of claim 1, wherein a pitch of the ridge is parallel to a longitudinal axis of the first casing.
 15. The heat exchanger of claim 1, wherein the heat exchanger core comprises a plurality of ridges, and a pitch of each ridge of the plurality of ridge is independently 0 degrees to 90 degrees with respect to the tangent direction.
 16. The heat exchanger of claim 1, wherein the heat exchanger core comprises a plurality of ridges, and a pitch of each ridge of the plurality of ridge is parallel to the longitudinal axis of the first casing.
 17. The heat exchanger of claim 1, wherein the first casing and the second casing each independently have a circular cross-sectional shape, an elliptical cross-sectional shape, an oval cross-sectional shape, a stadium cross-sectional shape, a semicircular cross-sectional shape, a square cross-sectional shape, a rectangular cross-sectional shape, a triangular cross-sectional shape, or combination thereof.
 18. The heat exchanger of claim 17, wherein the first casing and the second casing have a same cross-sectional shape, and wherein the second casing and the first casing are coaxial.
 19. The heat exchanger of claim 1, wherein the first casing and the second casing each independently have an average thickness of 0.5 centimeter to 5 centimeters.
 20. The heat exchanger of claim 1, wherein an aspect ratio of the flow passage is greater than 10, wherein the aspect ratio is a ratio of a height of the flow passage to a width of the flow passage, wherein the height is a distance between opposite surfaces a same ridge and is measured normal to a first ridge centerline, and wherein the width of the flow passage is measured from an inner surface of the second casing to an inner surface of the first casing.
 21. A method of manufacturing a heat exchanger core, the method comprising: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing comprising a slot; aligning the ridge and the slot by disposing the first casing on the second casing; rigidly attaching the ridge to the second casing; disposing a top head on a first end of the first casing and the second casing; disposing a bottom head on a second end of the first casing and the second casing; disposing an inlet on the first casing, the second casing, or a combination thereof; and disposing an outlet on the first casing, the second casing, or a combination thereof to manufacture the heat exchanger core, wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.
 22. The method of manufacturing the heat exchanger core of claim 21 wherein the providing the second casing comprising a slot comprises providing a metal sheet, cutting a slot in the metal sheet, wherein a direction of the slot forms an angle of 0 degrees to 90 degrees with respect to a longitudinal edge of the metal sheet, bending the metal sheet so that longitudinal edges of the metal sheet are adjacent each other, and joining the longitudinal edges to provide the second casing comprising the slot.
 23. The method of manufacturing the heat exchanger core of claim 21, wherein the providing the second casing comprising a slot comprises providing a metal pipe, cutting a slot in the metal pipe, wherein a direction of the slot forms an angle of 0 degrees to 90 degrees with respect to a tangent direction, wherein the tangent direction is perpendicular to a longitudinal axis of the metal pipe.
 24. The method of manufacturing the heat exchanger core of claim 21, wherein the ridge, the first casing, and the second casing define a helical flow passage.
 25. The method of manufacturing the heat exchanger core of claim 24, further comprising welding the ridge to the second casing.
 26. A method of manufacturing a heat exchanger core, the method comprising: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing member; disposing the second casing member on the first casing; rigidly attaching longitudinal edges of the second casing member to form a second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core; wherein the first casing and the second casing define a flow passage between the inlet and the outlet.
 27. The method of manufacturing the heat exchanger core of claim 26, wherein the disposing the second casing member on the first casing comprises wrapping the second casing member around the first casing.
 28. The method of manufacturing the heat exchanger core of claim 26, wherein the disposing the second casing member on the first casing comprises bending the second casing member and disposing the second casing member on an inner surface of the first casing.
 29. A method of manufacturing a heat exchanger core, the method comprising: providing a first casing and a second casing; deforming at least one of the first casing and the second casing to form a ridge on at least one of the second casing and the first casing; heating or cooling the first casing or the second casing to expand or contract at least one of the first casing and the second casing; disposing the first casing on the second casing; thermally equilibrating the first casing and the second casing to contact the first casing and the second casing; disposing a top head on an upper end of each of the second casing and the first casing; disposing a bottom head on a lower end of each of the second casing and the first casing; disposing an inlet on the second casing, the first casing, or combination thereof; disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core; wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.
 30. The method of manufacturing the heat exchanger core of claim 29, wherein the heating or cooling comprises heating the first casing to expand the first casing, and wherein the method further optionally comprises cooling the second casing to contract the second casing.
 31. The method of manufacturing a heat exchanger core of claim 29, wherein the heating or cooling comprises heating the second casing to expand the second casing, and wherein the method further comprises optionally cooling the second casing to contract the second casing.
 32. A method of manufacturing a heat exchanger core, the method comprising: providing a first casing; deforming the first casing to form a ridge on an inner surface of the first casing; providing a second casing, wherein an inner surface of the second casing comprises a groove, which is configured to receive the ridge; rotating the first casing relative to the second casing to thread the first casing into the second casing to dispose the first casing on the second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core, wherein the first casing and the second casing define a flow passage between the inlet and the outlet.
 33. A method of manufacturing a heat exchanger core, the method comprising: providing a first casing and a second casing; deforming at least one of the first casing and the second casing to form a ridge on at least one of an inner surface of the first casing and an inner surface of the second casing; disposing the first casing on the second casing; contacting the ridge and at least one of the inner surface of the first casing and the inner surface of the second casing; disposing a top head on an upper end of each of the first casing and the second casing; disposing a bottom head on a lower end of each of the first casing and the second casing; disposing an inlet on the second casing, the first casing, or combination thereof; and disposing an outlet on the second casing, the first casing, or combination thereof to manufacture the heat exchanger core, wherein the ridge, the first casing, and the second casing define a flow passage between the inlet and the outlet.
 34. The method of manufacturing the heat exchanger core of claim 33, wherein the deforming comprises deforming the first casing to form a ridge on the inner surface of the first casing, and wherein the contacting comprises contacting the ridge and an inner surface of the second casing by inserting the first casing into the second casing.
 35. The method of manufacturing a heat exchanger core of claim 33, wherein the disposing comprises disposing the first casing on the second casing; and then deforming the first casing to form a ridge on an inner surface of the first casing and to contact the ridge and an inner surface of the second casing.
 36. The method of manufacturing a heat exchanger core of claim 33, wherein the deforming comprises expanding the first casing in a direction towards the second casing.
 37. The method of manufacturing a heat exchanger core of claim 33, wherein the method comprises disposing the first casing within the second casing before the deforming.
 38. The method of manufacturing the heat exchanger core of claim 33, wherein the first casing is an inner casing, and wherein the second casing is an outer casing, or wherein the first casing is an outer casing, and wherein the second casing is an inner casing.
 39. The method of manufacturing the heat exchanger core of claim 33, wherein the deforming comprises deforming the inner wall of the first casing to form a ridge directed towards an inner wall of the second casing, and wherein the method further comprises forming a cut in an apex of the ridge, and welding the ridge to the inner wall of the second casing.
 40. A method of manufacturing a heat exchanger, the method comprising: providing the heat exchanger core according to claim 1; and disposing the heat exchanger core within a pressure vessel to manufacture the heat exchanger.
 41. The method of manufacturing a heat exchanger of claim 40, wherein the pressure vessel comprises a pressure vessel top head, a pressure vessel bottom head, and a shell disposed between the pressure vessel top head and the pressure vessel bottom head, wherein the pressure vessel top head, the pressure vessel bottom head, and the shell, or a combination thereof comprises a pressure vessel inlet, and wherein the pressure vessel top head, the pressure vessel bottom head, and the shell comprises a pressure vessel outlet.
 42. The method of manufacturing a heat exchanger of claim 40, wherein the pressure vessel inlet is disposed in the pressure vessel bottom head, and wherein the pressure vessel outlet is disposed in the pressure vessel top head.
 43. A method of transferring heat between a first fluid and a second fluid, the method comprising: providing a heat exchanger according to claim 1; directing a first fluid into the inlet of the inner casing; and directing a second fluid into the pressure vessel inlet to exchange heat between the first fluid and the second fluid. 